The present invention applies to stud welding guns and, more particularly, to improvements to stud welding guns utilizing automatic stud feeding equipment.
In the overall field of stud welding equipment, there is currently in use a general category of stud welding equipment consisting of hand held stud welding guns which utilize automatic stud feeding apparatus.
The overall components of such a system would be the hand held stud welding gun itself, an automatic stud chucking assembly carried by the stud welding gun and a stud loading assembly for delivering the studs to the automatic stud chucking assembly.
Positioned remote from the stud welding gun in such a system is the conventional stud welding power supply and controller which are electrically interconnected with the stud welding gun. Additionally, a stud orientator and stud feeder are utilized which feed the studs to the stud loading assembly by flexible feed tubes and also provide the pneumatic control for the stud chucking assembly.
The conventional stud chucking assembly is positioned on the front of the stud welding gun. The piston assembly is interconnected to the lift mechanism of the stud welding gun and includes a piston and piston rod. Interconnected to the end of the piston assembly is a stud receiving chamber which has a receiving chamber entrance through which studs to be loaded pass. The stud receiving chamber in conventional automatic feed stud welding guns is in the bottom or underneath the side of the stud receiving chamber and receives the studs in a slightly inclined vertically upward direction. Lastly, a conventional stud chuck is positioned on the opposite end of the stud receiving chamber.
The conventional stud loading assembly is positioned beneath the stud receiving chamber and is supported either upon the leg assembly of the stud welding gun or the stud receiving chamber itself. The stud loading assembly includes a stud loading tube, one end of which is connected to the stud feed tube and the other end which arcs upwardly into communication with the receiving chamber entrance of the stud receiving chamber. The stud loading assembly is secured to the stud welding gun by conventional threaded fasteners or other semi-permanent devices and is not readily detachable.
The conventional automatic stud welding equipment, in operation, will pneumatically dispatch a stud through the stud feed tube into the stud loading tube whereupon the stud is blown upwardly into the stud receiving chamber via the receiving chamber entrance. The stud is held in the stud receiving chamber by the air pressure blowing against the stud. Thereafter, the piston assembly is operated and the stud is pushed through the stud receiving chamber by the piston rod into the chuck preparatory to welding.
A typical use of such automatic stud welding equipment would be in welding heat transfer boiler tube studs inside of boilers and the like. In such applications, speed of operation is critical in that literally thousands of studs of identical configuration need be welded. The welding angle may be any angle from vertically downward, vertically overhead to any angle in between.
One of the problems that is being encountered in such conventional automatic stud welding equipment is that the stud, upon reaching the stud receiving chamber, will fall partially by gravity back out of the receiving chamber with a resultant jam occurring as the piston moves forward. This problem is more prevalent when the stud welding gun is held generally in the horizontal plane or side hand welding since gravity has a greater effect upon the stud at that position.
There are also problems encountered with the studs jamming in the stud loading tube prior to entrance into the stud receiving chamber and even in the stud feed tube.
Whenever a jam occurs, it is necessary in the conventional equipment to loosen the threaded fasteners and retract the stud loading tube from the assembly. Thereafter, the jam can be cleared and the stud loading tube reassembled into the stud loading assembly.
In clearing such jams after the stud loading tube is removed, it is common practice to cycle the stud welding gun through one or more cycles to confirm the operation of the gun. While the cycling is occurring, further studs are being fed through the stud feed tube and the stud loading tube. Inasmuch as the stud loading tube is disengaged from the stud feed assembly, a dangerous condition exists in that there is no restriction to the discharge of the studs from the stud loading tube by the pneumatic pressure. The discharge of the studs from the stud loading tube is at a rather high velocity and the studs become a dangerous projectile if proper care is not observed.
In summary, the conventional automatic stud welding equipment with the bottom feeding of studs to the stud receiving chamber provides a condition where gravity effect upon the studs can result in less reliable operation due to stud jamming. Further, the conventional equipment requires considerable time to disassemble and reassemble the stud loading tube from the stud loading assembly to clear a jam. Lastly, the conventional equipment provides a dangerous situation in that there is no safety to prevent discharge of the studs from the stud loading tube while the stud loading tube is disassembled and the stud welding gun is being cycled to clear the jam.